Doses of the insecticide "deltamethrin" that are tolerated by resistant mosquitoes can interfere with development of the malaria parasite in the stomach of the mosquito.
Insecticide-treated nets can prevent malaria despite mosquitoes developing resistance to the substances used on the nets, a study says. Insecticide resistance remains a major threat to malaria control.
"Our findings could help to explain why, so far, insecticide-treated nets seem to remain partly effective despite increasing resistance", said study author Jo Lines from the London school of hygiene and tropical medicine
The findings showed that the proportion of infected mosquitoes was significantly lower in the group that had been exposed to the insecticide and those that were infected developed fewer parasites than the unexposed group.
The study indicates that although resistant mosquitoes are surviving contact with the insecticide, the malaria parasites inside those mosquitoes are affected by the chemicals.
"This is a significant result. It suggests that the use of insecticide-treated nets might continue to reduce malaria even in areas where the mosquitoes have become resistant. If so, that would give us more time to develop alternatives," said Tarekegn Abeku, one of the researchers, from the London school of hygiene and tropical medicine.